Here's a Lion trick to use if you need 'constant' access to the your User Library folder, which Lion normally keeps hidden.
First, you have to get to your hidden Library folder. To do this:
1. Select the Finder's Go menu, hold down the Option key, then choose Library. A new finder window will appear with your Library folder highlighted.
2. Drag your Library folder to the sidebar. I insert my Library folder alphabetically between my DropBox folder and Movies folder, which I also drap there.
Now, simply by clicking Library in the sidebar, you will have access to your Library folder. This is great for easily getting to and emptying the Caches folder, whose often corrupted caches may slow down your computer.